How to resolve Ninja c++ build and execution - c++

Question

I have a C++ project based on CMake that uses Ninja. It's been build and ran using eclipse for C/C++. My current machine is a Mac OS.
The file:
#include <iostream>
#include <exception>
#include <string>
#include <stdexcept>
#include <vector>
#include <cmath>
using namespace std;
class Server {
private:
static int load;
public:
static int compute(long long A, long long B) {
load += 1;
if(A < 0) {
throw std::invalid_argument("A is negative");
}
vector<int> v(A, 0);
int real = -1, cmplx = sqrt(-1);
if(B == 0) throw 0;
real = (A/B)*real;
int ans = v.at(B);
return real + A - B*ans;
}
static int getLoad() {
return load;
}
};
int Server::load = 0;
int main() {
int T;
cin >> T;
while(T--) {
long long A, B;
cin >> A >> B;
/* Enter your code here. */
try{
cout << Server::compute(A, B) << endl;
} catch(invalid_argument e){
cout << "Exception: A is negative" << endl;
} catch(bad_alloc &e){
cout << "Not enough memory" << endl;
} catch(exception &e){
cout << "Exception: ";
cout << e.what() << endl;
} catch(...){
cout << "Other Exception" << endl;
}
}
cout << Server::getLoad() << endl;
return 0;
}
Build info:
cmake --build . -- -v
[1/2] /Library/Developer/CommandLineTools/usr/bin/c++ -O3 -DNDEBUG -isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX10.14.sdk -MD -MT CMakeFiles/deleteme.dir/deleteme.cpp.o -MF CMakeFiles/deleteme.dir/deleteme.cpp.o.d -o CMakeFiles/deleteme.dir/deleteme.cpp.o -c ../../deleteme.cpp
[2/2] : && /Library/Developer/CommandLineTools/usr/bin/c++ -O3 -DNDEBUG -isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX10.14.sdk -Wl,-search_paths_first -Wl,-headerpad_max_install_names CMakeFiles/deleteme.dir/deleteme.cpp.o -o deleteme && :
Build complete (0 errors, 0 warnings):
When I run:
Building in:
cmake --build . -- -v
ninja: no work to do.
Build complete (0 errors, 0 warnings):
It does not give me the chance to input the values. It just skips everything and finishes execution. If I put a cout right at the beginning, then the program works as expected.
Why is this happening?
Ps: The project complete path was removed from here for safety reasons. And yes, my project was created with the name 'deleteme'.
Pss: I took this snippet from HackerRank for studing purposes, so It should be fine. I've only added the try/catch and method call.

Answer 1

You are confusing building your program with running your program.
When you run the command cmake --build . -- -v, cmake will build your project. That means it will launch the appropriate tools to compile and link your program, which will produce an executable called deleteme somewhere in your build directory.
The subsequent invocation of the same command correctly reports that no work needs to be done (since you presumably haven't modified any of the source code between invocations).
To be clear, normally this will not run your program, which is why you don't get a prompt to input any values.
To run your program, which, if I understand correctly is what you are trying to do, simply run the executable deleteme that was produced by the build process. You will most likely find this executable in the build directory, that is, the directory where you ran the cmake --build . command. (Depending on your CMake project structure, you may also find it in a subdirectory of your build directory.)

Answer 2

I've figured It out how to solve this. I don't know what have caused It. It looks like ninja is not need if you have properly configured your environment variables, related to your compiler, inside Eclipse.
After doing that, everything works fine.